ES2662959B1 - Composite reinforcement material and obtaining procedure - Google Patents

Abstract

Composite reinforcement material and production method of a composite reinforcement material, of excellent mechanical strength. The method of producing a composite reinforcing material comprises a kneading step of at least one graphite-based carbon material and a reinforcing material in a base material. The graphite-based carbon material comprises a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), in which the rate between the rhombohedral graphite layer (3R) and the hexagonal graphite layer (2H) is of 31% or more.

Description

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List of Appointments Patent Bibliography

BGP 1: JP-A-2010-254822 ([0032] - [0038])

BGP 2: JP-A-2014-201676 ([0048] - [0064])

BGP 3: JP-A-2014-210916 ([0043])

BGP 4: WO 2014/064432 (Lines 4-9 on page 19)

BGP 5: JP-A-2013-079348 ([0083])

BGP 6: JP-A-2009-114435 ([0044])

Non-Patent Bibliography

BDP 1: Structural Change of Graphite with Griding; authors: Michio INAGAKI, Hisae MUGISHIMA and Kenji HOSOKAWA; February 1, 1973 (Received)

BDP 2: Changes of Probabilities P1, PABA, PABC with Heat Treatment of Carbons; authors: Tokiti NODA, Masaaki IWATSUKI and Michio INAGAKI; September 16, 1966 (Received)

BDP 3: Spectroscopic and X-ray diffraction studies on fluid deposited rhombohedral graphite from the Eastern Ghats Mobile Belt, India; G.Parthasarathy, Current Science, Vol. 90, No. 7, April 10, 2006

BDP 4: Classification of solid carbon materials and their structural characteristics; Nagoya Institute of Technology; Shinji KAWASAKI

Description of the invention Technical problem

However, the methods disclosed in Patent Bibliographies 1, 2 and 3 use graphite in commercially available flakes, which is hardly dispersed only by kneading due to the aggregating nature of graphite in flakes, so that the effect is not sufficiently obtained wanted. However, even when the graphite material (20% or more of the flakes of a single layer, 40% or more of the flakes of double or triple layers and less than 40% of the flakes of 10 layers or more) obtained by the method disclosed in Patent Bibliography 4 it was mixed in a solvent, the amount of graphene dispersed in the solvent was small, and only a dispersion of diluted graphene could be obtained. Additionally, although it is considered that a supernatant is collected and concentrated, it takes a long time for the treatments to repeat the stages of collecting and concentrating the supernatant, which is a problem of

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lower production efficiency of a graphene dispersion. As disclosed in Patent Bibliography 4, even subjecting natural graphite to ultrasound treatment for a long time, only weak parts of the surface are exfoliated; other large parts do not contribute to exfoliation and it is considered as a problem that the amount of graphene exfoliated is small.

Also, to increase the mechanical strength, a reinforcing material is generally added to a base material such as a polymer; however, depending on the amount of addition of a reinforcing material, the original properties (exterior appearance) of a polymer may be affected (Patent Bibliography 5).

In Patent Bibliographies 2 and 3 mentioned above, the physical properties that contribute to stiffness (hardness), such as the elastic modulus and impact resistance, are improved by adding a reinforcing material. Similar results were obtained in Example 5 of the present specification (invention not disclosed before making the present application).

In addition, in order to improve the strength of the traction (tensile strength), a reinforcing material has been added (eg, Patent Bibliography 1). In general, to increase tensile strength, a reinforcing material (a load) is suitably a wire type material that includes carbon fibers, glass fibers, cellulose fibers or the like. It has also been proposed that the elastic limit of traction be increased using a compatibilizer in order to prevent a wire type material from leaving the base material (Patent Bibliography 6). However, it has been found that mechanical strength and the like, which include tensile strength, etc., do not improve sufficiently just by adding a wire type material. The reason is considered to be that the base material is too soft for a thread type material to come out together with the base material.

As mentioned above, the problem is that the amount of graphene that is exfoliated is normally small by processing natural graphite without any treatment. However, as a result of more recent studies, carrying out predetermined treatments of graphite that serves as a source of material, a graphite-based carbon material (a precursor of graphene) is obtained, from which graphene is easily exfoliated, being Graphene capable of dispersing at a high concentration or to a high degree. Part or all of the graphene precursor is exfoliated by ultrasonic waves, stirring and kneading to produce a mixed material that is "graphene-like graphite," which contains graphene precursor to graphene. The size, thickness, etc.

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Graphene type graphite is not limited, since they are variables that depend on the amount of addition, the process time, etc. of the graphene precursor. However, it is preferred that the graphite of the graphene type is more in flakes. That is, in other words, the graphite-based carbon material (the graphene precursor) is graphite capable of easily exfoliating and dispersing as a graphite of graphene type by known agitation and kneading processes or devices.

It has been discovered that by dispersing a small amount of graphene-type graphite together with a reinforcing material in a base material, mechanical strength could be improved, such as a flexural modulus, compressive strength, tensile strength and Young's modulus. In addition, it was discovered that the composite reinforcing material could be produced without substantially changing the conventional production method.

The invention has been completed focusing on such problems and an object of the invention is to provide a composite reinforcement material and a method of obtaining said reinforcing material excellent in mechanical strength.

Another object of the invention is to provide a composite reinforcing material capable of displaying the desired characteristics even if the amount of graphene-type graphite dispersed / added in a base material is small.

A further object of the invention is to provide an excellent composite reinforcement material in mechanical strength using a conventional production process.

Solution to the problem

To solve the problems described above, the present invention is a method of obtaining a composite reinforcing material, which comprises dispersing at least one carbon material based on graphite and a reinforcing material on a base material, thus exfoliating a part or the whole of said graphite-based carbon material,

the graphite-based carbon material having a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), where the Proportion (3R) of the rhombohedral graphite layer (3R) and the hexagonal graphite layer ( 2H), based on an X-ray diffraction method that is defined by the following Equation 1, is 31% or more:

Proportion (3R) = P3 / (P3 + P4) * 100 •••• (Equation 1)

in which

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P3 is the peak intensity of a plane (101) of the rhombohedral graphite layer (3R) based on the X-ray diffraction method, and

P4 is the peak intensity of a plane (101) of the hexagonal graphite layer (2H) based on the X-ray diffraction method.

In another embodiment, the invention is the composite reinforcing material that is obtained by dispersing at least one carbon material based on graphite and a reinforcing material on a base material, thus exfoliating a part or all of said carbon based material. in graphite, according to the previous method.

That is, the composite reinforcing material of the present invention comprises graphene-type graphite exfoliated from a graphite-based carbon material, and a reinforcing material, dispersed in a base material,

characterized by the graphite-based carbon material by having a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), in which the Proportion of the rhombohedral graphite layer (3R) and the hexagonal graphite layer ( 2H), based on an X-ray diffraction method that is defined by the following Equation 1, is 31% or more:

Proportion (3R) = P3 / (P3 + P4) * 100 •••• (Equation 1) in which

P3 is the peak intensity of a plane (101) of the rhombohedral graphite layer (3R) based on the X-ray diffraction method and

P4 is the peak intensity of a plane (101) of the hexagonal graphite layer (2H) based on the X-ray diffraction method.

According to the invention, the composite material is excellent in mechanical strength. This is because it is speculated that the effect of increasing the elastic modulus of a base material itself and the effect of preventing the reinforcing material from coming out were synergistically exhibited by dispersing graphene-type graphite in a base material. Among the parameters that measure mechanical strength such as the flexural modulus, compressive strength, tensile strength and Young's modulus, the composite material is excellent in tensile strength, as an example.

The reinforcing material is characterized by being a microparticle in the form of wire, linear or flake type.

According to the invention, the microparticle is surrounded by graphite of graphene type. In this way a strengthening function of the microparticle can be sufficiently exercised.

The microparticle is characterized by having an aspect ratio of 5: 1 or more.

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In accordance with the invention, a strengthening function of the microparticle can also be sufficiently exercised.

The weight ratio of the sum of the graphite-based carbon material and the graphene-based graphite with respect to the reinforcing material is characterized by being 1/100 or more and less than 10.

According to the invention, a reinforcing function of the reinforcing material can be effectively exercised.

The base material is characterized by being a polymer.

According to the invention, an excellent composite reinforcement material in mechanical strength can be obtained.

The base material is characterized by being an inorganic material.

According to the invention, an excellent composite reinforcement material in mechanical strength can be obtained.

The molding material is characterized by comprising the composite reinforcing material.

According to the invention, a molding material used for 3D printing and the like, excellent in mechanical strength, can be obtained.

Brief description of the figures

{Fig. 1} Figure 1 shows the crystalline structure of graphite, where (a) refers to the crystalline structure of hexagonal crystals and (b) refers to the crystalline structure of rhombohedral crystals.

{Fig. 2} Figure 2 shows the X-ray diffraction profile of general natural graphite.

{Fig. 3} Figure 3 illustrates the production apparatus A using the jet and plasma mill of Example 1.

{Fig. 4} Figure 4 illustrates the production apparatus B using the ball mill and magnetron of Example 1, where (a) is a diagram illustrating the state of pulverization and (b) is a diagram illustrating the state where They collect graphite-based carbon materials (precursors).

{Fig. 5} Figure 5 shows the X-ray diffraction profile of the graphite-based carbon material of Sample 5 produced by the production apparatus B according to Example 1.

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{Fig. 6} Figure 6 shows the X-ray diffraction profile of the graphite-based carbon material of Sample 6 produced by the production apparatus A according to Example 1.

{Fig. 7} Figure 7 shows the X-ray diffraction profile of the graphite-based carbon material of Sample 1 indicating a comparative example.

{Fig. 8} Figure 8 shows the dispersion producing apparatus that obtains a dispersion using a graphite-based carbon material as a precursor.

{Fig. 9} Figure 9 shows the dispersion states of the dispersions produced using the graphite-based carbon materials of Sample 1 indicating a comparative example, and of Sample 5 that was produced using the production apparatus B of Example 1 .

{Fig. 10} Figure 10 is a MET image of a carbon material based on graphite (graphene) dispersed in a dispersion.

{Fig. 11} Figure 11 shows the distribution states of the graphite-based carbon material dispersed in a dispersion that was produced using the graphite-based carbon material (precursor) of Sample 5, where (a) is a diagram showing The average size distribution, while (b) is a diagram showing the distribution of the number of layers.

{Fig. 12} Figure 12 shows the state of distribution of a graphite-based carbon material dispersed in the dispersion that was produced using the graphite-based carbon material of Sample 1 indicating the comparative example, where (a) is a diagram that shows the average size distribution, and (b) is a diagram that shows the distribution of the number of layers.

{Fig. 13} Figure 13 shows the distributions of the number of layers of the graphite-based carbon materials each dispersed in dispersions that were produced using Samples 1 to 7 as precursors.

{Fig. 14} Figure 14 shows the proportions of graphene having 10 or less layers of rhombohedral crystals dispersed in a dispersion.

{Fig. 15} Figure 15 shows the state of graphite distribution when the conditions for producing a dispersion using the graphite-based carbon material (precursor) of Sample 5 according to Example 2 are varied, where (a) is a diagram showing the distribution in a case where an ultrasonic treatment and a microwave treatment were combined, while (b) is a diagram showing the distribution of the number of layers in a case where an ultrasound treatment was only carried out .

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{Fig. 16} Figure 16 shows the resistance value when the graphite-based carbon material of Example 3 was dispersed in a conductive ink.

{Fig. 17} Figure 17 shows the tensile strength when the graphite-based carbon material of Example 4 was kneaded with a resin.

{Fig. 18} Figure 18 shows the elastic modulus when the graphite-based carbon material of Example 5 was kneaded with a resin.

{Fig. 19} Figure 19 shows distribution states of the graphite-based carbon material in a dispersion, dispersed in N-methylpyrrolidone (NMP), to provide a supplementary description of the dispersion state of Example 5, where (a) is the state of distribution of sample 12 and (b) is the state of distribution of sample 2.

{Fig. 20} Figure 20 shows the tensile strength and flexural modulus of the test piece of Example 6.

{Fig. 21} Figure 21 is a photographed image of SEM (plan view) of a graphene precursor.

{Fig. 22} Figure 22 is a photographed image of SEM (profile view) of a graphene precursor.

{Fig. 23} Figure 23 is a photographed image of SEM (cross-sectional view) of a resin in which graphene-type graphite is dispersed.

{Fig. 24} Figure 24 is a side image photographed of SEM (profile view) of graphene-type graphite in Figure 23.

{Fig. 25} Figure 25 shows the tensile strength and flexural modulus of the test piece of Example 7.

{Fig. 26} Figure 26 shows the tensile strength and flexural modulus of the test piece of Example 8 in which a shape of a reinforcing material was changed.

{Fig. 27} Figure 27 is a schematic view illustrating the form of the reinforcing material of Example 8, where (a) is the form of glass fibers and carbon fibers, (b) is the form of talc and (c) is the shape of silica

{Fig. 28} Figure 28 shows the tensile strength and flexural modulus of the test piece of Example 9 in which the ratio of graphene precursor mixture to reinforcement material was changed.

Description of the realizations

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The invention focuses on the crystalline structure of graphite and, first of all, issues related to said crystalline structure will be explained. It is known that natural graphite is classified into three types of crystalline structures, namely hexagonal crystals, rhombohedral crystals and disordered crystals, depending on the way in which the layers overlap. As shown in Figure 1, the hexagonal crystals have a crystalline structure in which the layers are arranged in the order of ABABAB-, while the rhombohedral crystals have a crystalline structure in which the layers are arranged in the order of ABCABCABC -.

In natural graphite, there are almost no rhombohedral crystals at the stage in which it is excavated. However, approximately 14% of rhombohedral crystals generally exist in natural graphite-based carbon materials because they are carried out pulverization or the like in the purification stage. In addition, it is known that the proportion of rhombohedral crystals converges by approximately 30% even when spraying is carried out for a prolonged period of time (Non-Patent Bibliography 1 and 2).

In addition, a method has been described in which graphite is expanded by heating, rather than with physical forces such as pulverization, thereby breaking into flakes of graphite. However, even when graphite is treated at a temperature of approximately 1300 ° C (1600 K), the proportion of rhombohedral crystals is approximately 25% (Non-Patent Bibliography 3). Additionally, the proportion is up to approximately 30% even when an extremely high temperature of 3000 ° C is applied (Non-Patent Bibliography 2).

Therefore, although it is possible to increase the proportion of rhombohedral crystals by treating natural graphite with physical forces or heat, the upper limit is approximately 30%.

Hexagonal crystals (2H), which exist in natural graphite at a high level, are very stable, and the interlayer force of van der Waals between its graphene layers is shown in Equation 3 (Patent Bibliography 2). By applying an energy that exceeds this force, graphene exfoliates. The energy required for exfoliation is inversely proportional to the thickness cube. Therefore, in a thick state where numerous layers overlap, graphene is exfoliated by a weak physical force, such as very weak ultrasound waves. However, in the case where graphene is exfoliated from a somewhat thin graphite, a very large energy is required. In other words, even if

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Graphite is treated for a long time, only weak parts of the surface are exfoliated, and large parts remain without exfoliating.

Fvdw = H-A / (6rc-t3) •••• Equation 3

Fvdw: force of van der Waals H: Hamaker constant A: Surface area of graphite or graphene t: Thickness of graphite or graphene

The present inventors succeeded in increasing the proportion of rhombohedral crystals (3R) up to 30% or more by carrying out predetermined treatments of natural graphite, as shown below. This percentage had only reached 30% by spraying or heating treatments at an extremely high temperature. The following discoveries were obtained as results of experiments and studies. That is, when the content of rhombohedral crystals (3R) in a graphite-based carbon material is higher, particularly when the content is 31% or more, there is a tendency for graphene to be easily exfoliated by using said Graphite-based carbon material as a precursor, thereby easily obtaining a highly concentrated and dispersed graphene dispersion. Due to this reason, it is considered that when a shear force or similar is applied to the rhombohedral crystals (3R) a deformation occurs between the layers, that is to say that the deformation in the entire structure of the graphite becomes large, and the graphene becomes Exfoliates easily regardless of van der Waals forces. Consequently, in the invention, a graphite-based carbon material from which graphene is easily exfoliated by carrying out predetermined treatments on natural graphite, and which makes it possible to disperse graphene in a high concentration or in a high degree , is called a graphene precursor. Next in the present document and in the same order in the examples, a method for producing a graphene precursor with predetermined treatments, a crystalline structure of the graphene precursor and a graphene dispersion using the graphene precursor will be described.

At this point, in the specification, a graphene refers to a graphene of the flake type or of the lamina type, which is a crystal of an average size of 100 nm or more, but which is not a fine crystal of an average size of several nanometers to tens of nanometers, and it has 10 layers or less.

Additionally, as graphene is a crystal with an average size of 100 nm or more, when artificial graphite and carbon black, which are carbon materials

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amorphous (microcrystalline) different from natural graphite, are treated evenly, graphene cannot be obtained (Non-Patent Bibliography 4).

Further, in the specification, a graphene compound means a composite material that is produced using the graphite-based carbon material useful as a graphene precursor according to the invention, that is, a graphite-based carbon material that it has a Proportion (3R) of 31% or more (for example, Samples 2-7 of Example 1, samples 2, 21, ••• of Example 5, described below).

Hereinafter, examples for carrying out the composite reinforcing material and the molding material in accordance with the present invention will be described.

Example 1

<Regarding the production of a graphite-based carbon material useful as a graphene precursor>

A method for obtaining a graphite-based carbon material useful as a graphene precursor will be explained by a production apparatus A using the jet and plasma mill shown in Figure 3. As an example, the production apparatus A refers to a case in which plasma is applied for a first treatment based on the force of radio waves, and in which the jet mill is used for a second treatment based on physical forces.

In Figure 3, the symbol 1 refers to a particle of 5 mm or less of a natural graphite material (graphite in ACB-50 flakes manufactured by Nippon Graphite Industries, Ltd.); symbol 2 refers to a hopper that stores the natural graphite material 1; symbol 3 refers to a Venturi nozzle that discharges the natural graphite material 1 from the hopper 2; symbol 4 refers to a jet mill that injects jets of the air that has been pumped from a compressor 5, dividing into eight places, to thereby allow the natural graphite material to collide against the inside of a chamber by a jet blown; and the symbol 7 refers to a plasma generator that pulverizes a gas 9, such as oxygen, argon, nitrogen or hydrogen, through a nozzle 8 from a tank 6 and that applies a voltage to a coil 11, wound around the outer periphery of the nozzle 8, from a high voltage power supply 10, thereby generating plasma inside the chamber of the jet mill 4, and the plasma generator is provided in each of the four locations in The inside of the camera. Symbol 13 refers to a pipe that connects the jet mill 4 and a dust collector 14; symbol 14 refers to a dust collector; the symbol

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15 refers to a collection vessel; symbol 16 refers to a graphite-based carbon material (graphene precursor); and symbol 17 refers to a blower.

Next, the production method will be explained. The conditions for the jet mill and plasma are as follows.

The conditions for the jet mill are as follows.

Pressure: 0.5 MPa

Air volume: 2.8 m3 / min

Inner diameter of the nozzle: 12 mm

Flow rate: approximately 410 m / s

The conditions for plasma are as follows.

Power: 15 W Voltage: 8 kV

Gas species: Ar (purity of 99.999% by volume)

Gas flow: 5 l / min

It is considered that the natural graphite materials 1, which have been loaded into the chamber of the jet mill 4 from the Venturi nozzle 3, accelerate to the speed of sound or more inside the chamber, and are sprayed by the impact between natural graphite materials 1 or their impact against the wall, and that, simultaneously, plasma 12 discharges an electric current or excites natural graphite materials 1, acts directly on atoms (electrons) and increases the deformations of the crystals, thereby promoting pulverization. When the natural graphite materials 1 become fine particles of a certain particle diameter (approximately 1 to 10 pm), their mass is reduced, the centrifugal force weakens and, consequently, the natural graphite materials 1 are pumped outside the pipe 13 which is connected to the center of the chamber.

A gas that includes graphite-based carbon materials (graphene precursors), which has been flowed from the pipeline 13 into a cylindrical vessel of the dust collector chamber 14, forms a spiral flow, and drops the materials made of graphite-based carbon 16, which collides with the inner wall of the container, to a collection vessel 15 below, while an upward air flow is generated in the center of the chamber due to a tapered part of the container in the part bottom of the chamber, and the gas is emitted from blower 17 (called the cyclone effect). According to the production apparatus A in this example, approximately 800 g of a graphene precursor from 1 kg of the raw materials is used, i.e.

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natural graphite materials 1. The graphite-based carbon material (graphene precursors) 16 (recovery efficiency: approximately 80%) was obtained.

Next, based on the production apparatus B using the ball mill and microwaves shown in Figure 4, a method for obtaining a graphite-based carbon material that is useful as a graphene precursor will be described. The apparatus B refers, as an example, to a case where microwaves are applied as the first treatment based on radio wave forces and where a ball mill is used for the second treatment based on physical forces.

In Figure 4 (a) and (b), symbol 20 refers to the ball mill; symbol 21 refers to a microwave generator (magnetron); symbol 22 refers to a waveguide; symbol 23 refers to a microwave input; symbol 24 refers to a medium; symbol 25 refers to particles of 5 mm or less of a natural graphite material (graphite in ACB-50 flakes manufactured by Nippon Graphite Industries, Ltd.); symbol 26 refers to a collection vessel; symbol 27 refers to a filter; and symbol 28 refers to a graphite-based carbon material (graphene precursors).

Next, the production method will be explained. The conditions for the ball mill and the microwave generator are as follows.

The conditions for the ball mill are as follows.

Rotation speed: 30 rpm Medium size: ^ 5 mm Medium species: zirconia balls Spraying time: 3 hours

The conditions for the microwave generator (magnetron) are as follows.

Power: 300 W

Frequency: 2.45 GHz

Irradiation Method: Intermittent

1 kg of natural graphite carbon raw materials 25 and 800 g of medium 24 are loaded into the ball mill chamber 20, the chamber is closed, and the mixture is treated with a rotation speed of 30 rpm for 3 hours . During the first treatment, the camera is irradiated with microwave intermittently (for 20 seconds every 10 minutes). Microwave irradiation is considered to act directly on the atoms (electrons) of the raw materials, thereby increasing the deformations of the crystals. After the treatment, the means 24 are removed by the filter 27 and, in this way, a powder of

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approximately 10 pm of graphite-based carbon materials (precursors) 28 in collection vessel 26.

<Regarding the X-ray diffraction profile of graphite-based carbon materials (graphene precursors)>

With reference to Figures 5 to 7, X-ray diffraction profiles and crystalline structures will be described with respect to natural graphite-based materials (Samples 6 and 5) produced by production apparatus A and B, and the powder of approximately 10 pm of natural graphite-based materials (Sample 1: comparative example) that were obtained using only the ball mill of the production apparatus B.

The measurement conditions for the X-ray diffraction apparatus are as

follow.

Source: Ka de Cu rays

Scanning Speed: 20 ° / min

Tube voltage: 40 kV

Tube current: 30 mA

According to the X-ray diffraction method (multi-purpose X-ray diffractometer with horizontal mounting of the Ultima IV model sample manufactured by Rigaku Corporation), each sample presents the peak intensities P1, P2, P3 and P4 in the planes (100 ), (002) and (101) of the 2H hexagonal crystals and in the plane (101) of the 3R rhombohedral crystals. Hereinafter, said peak intensities will be explained.

In this document, X-ray diffraction profile measurements have used the so-called standardized values in the country and abroad in recent years. This multi-purpose X-ray diffractometer with horizontal mounting of the Ultima IV model sample manufactured by Rigaku Corporation is a device that can measure the X-ray diffraction profile according to JIS R 7651: 2007 “Measurement of lattice parameters and crystallite sizes of carbon materials ”. In addition, Proportion (3R) is the ratio between the intensity of the diffraction obtained with the Ratio (3R) = P3 / (P3 + P4) x 100; even if the diffraction intensity value is changed, the value of the Ratio (3R) does not change. This means that the ratio of the intensity of the diffraction is standardized and its value does not depend on the measuring devices, which is commonly used to avoid carrying out the identification of the substance of absolute value.

As shown in Figure 5 and Table 1, Sample 5 produced by the production apparatus B, which applies a treatment with a ball mill and a treatment with

microwave, had high proportions of peak intensities P3 and P1, and a Proportion (3R) defined by Equation 1 showing a proportion of P3 for a sum of P3 and P4 of 46%. Additionally, the ratio between the P1 / P2 intensities was 0.012. Proportion (3R) = P3 / (P3 + P4) * 100 •••• Equation 1 5 in which

P1 is the peak intensity of a plane (100) of the hexagonal graphite layer (2H) based on the X-ray diffraction method,

P2 is the peak intensity of a plane (002) of the hexagonal graphite layer (2H) based on the X-ray diffraction method,

10 P3 is the peak intensity of a plane (101) of the rhombohedral graphite layer

(3R) based on the X-ray diffraction method and

P4 is the peak intensity of a plane (101) of the hexagonal graphite layer (2H) based on the X-ray diffraction method.

{Table 1}

 Peak Intensities [gradol counts (29 [° D

 Hexagonal crystals 2H (100) [P1]

 162 (42.33)

 Hexagonal crystals 2H (002) [P2]

 13157 (26.50)

 3R rhombohedral crystals (101) [P3]

 396 (43.34)

 Hexagonal crystals 2H (101) [P4]

 466 (44.57)

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In the same way, as shown in Figure 6 and Table 2, Sample 6 produced by the production apparatus A, which applies a treatment based on the jet mill and a plasma based treatment, had large proportions of intensities. P3 and P1 peak, and Proportion (3R) was 51%. In addition, the intensity ratio 20 P1 / P2 was 0.014.

{Table 2}

 Peak Intensities [counts • grade] (29 [° D

 Hexagonal crystals 2H (100) [P1]

 66 (42.43)

 Hexagonal crystals 2H (002) [P2]

 4675 (26.49)

 3R rhombohedral crystals (101) [P3]

 170 (43.37)

 Hexagonal crystals 2H (101) [P4]

 162 (44.63)

Additionally, as shown in Figure 7 and Table 3, Sample 1 indicating a comparative example only with the ball mill had a small proportion

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P3 peak intensity compared to Samples 5 and 6, and Proportion (3R) was 23%. In addition, the ratio of P1 / P2 intensities was 0.008.

{Table 3}

 Peak Intensities [counts • grade] (20 [°])

 Hexagonal crystals 2H (100) [P1]

 120 (42.4)

 Hexagonal crystals 2H (002) [P2]

 15000 (26.5)

 3R rhombohedral crystals (101) [P3]

 50 (43.3)

 Hexagonal crystals 2H (101) [P4]

 160 (44.5)

Therefore, Sample 5 produced by the production apparatus B of Example 1, and Sample 6 produced by the production apparatus A of Example 1 had Proportions (3R) of 46% and 51%, respectively, and it was demonstrated that their Proportions (3R) were 40% or more, or 50% or more, compared to the natural graphite shown in Figure 2 and Sample 1, which indicate a comparative example.

Subsequently, graphene dispersions were produced using the graphene precursors previously produced, and their ease in graphene exfoliation was evaluated. <As for graphene dispersions>

A method for producing a graphene dispersion will be explained with reference to Figure 8. Figure 8 shows, as an example, a case where an ultrasonic treatment and a microwave treatment are combined in a liquid when a graphene dispersion occurs.

(1) 0.2 g of a graphite-based carbon material useful as a precursor to graphene and 200 ml of N-methylpyrrolidone (NMP) are loaded as a dispersion medium in a beaker 40.

(2) The beaker 40 is placed inside a chamber 42 of a microwave generator 43, and an ultrasonic vibrator 44A of an ultrasonic horn 44 is inserted into the dispersion means 41 from the upper direction.

(3) The ultrasonic horn 44 is activated, and 20 kHz (100 W) ultrasound waves are applied to it continuously for 3 hours.

(4) While the previous ultrasonic horn 44 is activated, the microwave generator 43 is activated to apply to the same 2.45 GHz (300 W) microwave intermittently (irradiation for 10 seconds every 5 minutes).

Figure 9 refers to the appearance of graphene dispersions produced in the manner described above when 24 hours have passed.

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Although a portion of the graphene dispersion 30 was deposited using Sample 5 produced by the production apparatus B, a product that completely shows a black color was observed. Therefore, a large portion of the graphite-based carbon materials that are used as graphene precursors are considered to be dispersed in a state where graphene is exfoliated from them.

In dispersion 31 using Sample 1 indicating a comparative example, most of the graphite-based carbon materials were deposited, and it was confirmed that a portion thereof floated as a supernatant. From the facts, graphene is considered to be exported from a small portion thereof and that it floated as the supernatant.

In addition, the graphene dispersion produced in the manner described above was diluted to an observable concentration, applied as a coating on a sample holder (MET grid), and the grid dried. In that way, the size and number of graphene layers were observed in the image captured by transmission electron microscope (MET), as shown in Figure 10. In addition, the grid coated with the diluted supernatant was used for the Sample 1. For example, in the case of Figure 10, the size corresponds to a maximum length L of a snowflake 33, which averages 600 nm, based on Figure 10 (a). Regarding the number of layers, in Figure 10 (b) the final face of the flake 33 was observed, and the graphene layers superimposed were counted, to calculate in this way the number of layers as 6 layers (one portion indicated by symbol 34). In this way, the size and number of layers with respect to each flake were measured ("N" indicates the number of flakes) and the numbers of graphene layers and the sizes shown in Figures 11 and 12 were obtained.

With reference to Figure 11 (a), the distribution of particle sizes (distribution of sizes) of thin flakes included in the graphene dispersion of Sample 5 (Proportion (R3) of 46%) produced by the production apparatus B from Example 1 it had a peak at 0.5 pm. In addition, in Figure 11 (b), regarding the number of layers, a distribution was observed that had a peak in 3 layers and in which graphene with 10 layers or less was 68%.

With reference to Figure 12, the distribution of particle sizes (distribution of sizes) of thin flakes included in the dispersion of Sample 1 (Proportion (R3) of 23%) of the comparative example had a peak at 0.9 pm. In addition, as regards the number of layers, a distribution was observed in which graphene with 30 layers or more occupied the largest portion and in which graphene with 10 layers or less was 10%.

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From these results, it was revealed that when the product of Sample 5 produced by the apparatus B was used as a graphene precursor, a highly concentrated graphene dispersion containing a lot of graphene of 10 layers or less and of excellent dispersibility can be obtained .

Next, with reference to Figure 13, a relationship between the Proportion (3R) of the graphene precursor and the number of layers in the graphene dispersion will be described. Samples 1, 5 and 6 of Figure 13 are those described above. Samples 2, 3 and 4 were produced by the production apparatus B which carried out a treatment based on a ball mill and a microwave treatment, and were graphene dispersions that were produced using precursors that had been obtained over time. of irradiation with microwave shorter than for Sample 5. In addition, Sample 7 was produced using the production apparatus A which carried out a treatment based on a jet mill and a plasma treatment, and was a graphene dispersion that It was produced using a precursor that had been obtained by applying plasma of a higher potency than for Sample 6.

According to Figure 13, with respect to Samples 2 and 3 with Proportions (3R) of 31% and 38% respectively, the distributions of the number of layers have peaks in approximately 13 layers; that is, the forms of the distributions are close to those of a normal distribution (dispersions using Samples 2 and 3). With respect to Samples 4 to 7 showing Proportions (3R) of 40% or more, the distributions of the number of layers have peaks in several times the number of layers (thin graphene); that is, the forms of the distributions are those of a so-called lognormal distribution. On the other hand, with respect to Sample 1 which has a Proportion (3R) of 23%, its distribution has a peak in 30 layers or more (the dispersion using Sample 1). That is, the following is understood: there is a tendency that, in cases where the Proportion (3R) reaches 31% or more, the shapes of the number of layers distributions differ from those in cases where the Proportion (3R) is less than 31%; and also, in the cases where the Proportion (3R) reaches 40% or more, the shapes of the number of layers distributions clearly differ from those of the cases where the Proportion (3R) is less than 40%. In addition, it can be understood that, as regards graphene ratios of 10 layers or less, the Proportion (3R) of the dispersion used in Sample 3 is 38%, while the Proportion (3R) of the dispersion that Use Sample 4 is 62%, and when the Proportion (3R) reaches 40% or more, the graphene ratio of 10 layers or less rapidly increases.

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From these facts, graphene of 10 layers or less can easily be exfoliated in cases where Proportion (3R) is 31% or more, and that, as the Proportion (3R) increases up to 40 %, 50% and 60%, graphene of 10 layers or less exfoliates more easily. In addition, focusing on the P1 / P2 intensity ratio, Samples 2 to 7 show values within a comparatively narrow range of 0.012 to 0.016, and all of them are preferable because they exceed 0.01, where graphene is considered to be Exfoliates easily as crystalline structures deform.

In addition, the results obtained by comparing the Proportions (3R) and graphene proportions of 10 layers or less included therein are shown in Figure 14. With reference to Figure 14, it was revealed that when the Proportion (3R ) reached 25% or more, around 31%, graphene of 10 layers or less began to increase (showing an ever increasing slope). In addition, it was revealed that, at approximately 40%, graphene of 10 layers or less increased rapidly (in terms of graphene ratios of 10 layers or less, while the Proportion (3R) of the dispersion in which Sample 3 was used was 38%, the Proportion (3R) of the dispersion in which Sample 4 was used was 62%, and the graphene ratio of 10 layers or less increased rapidly by 24% when the Proportion (3R) increase by 4%), and that the percentage of graphene of 10 layers or less compared to the total graphene was 50% or more. In addition, the black square dots in Figure 14 each correspond to different samples, and Samples 1 to 7 described above and other samples are included there.

From these facts, when a sample using a Proportion (3R) of 31% or more is used as a graphene precursor to produce a graphene dispersion, the distributed graphene ratio of 10 layers or less begins to increase; In addition, when a sample using a Proportion (3R) of 40% or more is used as a graphene precursor to produce a graphene dispersion, 50% or more graphene of 10 layers or less is produced. In other words, a graphene dispersion can be obtained in which graphene is highly concentrated and highly dispersed. Additionally, as the graphite-based carbon materials (precursors) included in the dispersion described above are hardly deposited, a concentrated graphene dispersion can be easily obtained. According to this method, even a graphene dispersion can be produced whose graphene concentration exceeds 10% without concentrating it. Particularly, the Ratio (3R) is preferably 40%

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or more from a point of view that the proportion of graphene dispersed of 10 layers or less is sharply increased to 50% or more.

The above description clarifies the following: when the Proportion (3R) is 31% or more, preferably 40% or more, and also preferably 50% or more, in many cases graphene separation of 10 layers or less and materials Thin carbon-based graphite of approximately 10 layers occurs in a larger proportion; and in the case where these graphite-based carbon materials are used as graphene precursors, a highly concentrated graphene dispersion can be obtained which has excellent graphene dispersibility. Even further, Example 5, which will be described below, clarifies that, in the case where Proportion (3R) is 31% or more, graphite-based carbon materials are useful as graphene precursors.

Furthermore, it is considered that an upper limit for Proportion (3R) does not particularly define said upper limit. However, it is preferable that the upper limit be defined in such a way that the intensity ratio P1 / P2 simultaneously satisfies 0.01 or more, because graphene precursors are easily exfoliated when a dispersion or the like occurs. In addition, in the case of production methods using production A and B devices, the upper limit is approximately 70%, from the point of view that graphene is easily produced. In addition, a method that combines a treatment based on the jet mill of the production apparatus A and a plasma treatment is more preferable, because a graphene precursor having a higher Proportion (3R) can be easily obtained. Additionally, Proportion (3R) provided it reaches 31% or more, combining treatment based on physical forces and treatment based on radio wave forces.

Example 2

Example 1 explains a case in which the ultrasonic treatment and the microwave treatment were combined to obtain a graphene dispersion. In Example 2, only one ultrasonic treatment was carried out while no microwave treatment was carried out, and the other conditions were the same as in Example 1.

Figure 15 (b) shows the distribution of a number of layers with respect to the graphene dispersion that was obtained by carrying out an ultrasound treatment using the graphene precursor of Sample 5 (Proportion (3R) = 46%) which was produced by production apparatus B. In addition, Figure 15 (a) is the same as the

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distribution shown in Figure 11 (b) of Sample 5 produced by the production apparatus B of Example 1.

As a result, although the trend of the distribution of the number of layers was almost similar, the proportion of graphene of 10 layers or less was 64%, slightly reduced compared to 68% in Example 1. From this fact, It revealed that it was more effective to carry out both treatments simultaneously based on a physical force and a force imposed by radio waves to produce a graphene dispersion.

Example 3

In Example 3, an example used for a conductive ink will be described.

Sample 1 (Proportion (3R) = 23%), Sample 3 (Proportion (3R) = 38%), Sample 5 (Proportion (3R) = 46%) and Sample 6 (Proportion (3R) = 51%) were used of Example 1 as graphene precursors in a mixed solution of water and a carbon number alcohol of 3 or less, which served as an agent to confer conductivity, in concentrations adapted for conductive inks, thus producing: INK1, INK3, INK5 and TINTA6, and their resistance values were compared. Based on the results, as the Proportions (3R) increased, the resistance values were lower.

Example 4

In Example 4, an example in which a graphene precursor was kneaded with a resin will be explained.

When a resin sheet was produced, in which graphene was dispersed, the tensile strength was much higher even if glass fibers were added thereto. Therefore, a factor for this was studied and, consequently, it was found that the simultaneous addition of a compatibilizer with glass fibers contributed to the formation of graphene from the precursor. Therefore, the products obtained by mixing dispersing agents and a compatibilizer were studied in a resin.

1% by weight of Sample 5 (Proportion (3R) = 46%) of Example 1 was added as a precursor directly to LLDPE (polyethylene), and the mixture was kneaded while shearing (a shear force) was applied thereto with a kneader, a two-axis kneader (extruder) or the like.

It is public knowledge that, when a graphite-based carbon material is converted to graphene, being highly dispersed in a resin, the

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tensile strength. Therefore, by measuring the tensile strength of the resin, the degrees of exfoliation for graphene and dispersion can be estimated relatively. Tensile strength was measured with an exact general purpose bench test machine (AUTOGRAPH AGS-J) manufactured by Shimadzu Corporation under test speed conditions of 500 mm / min.

In addition, to compare the degree of exfoliation to give graphene and dispersibility depending on the presence or absence of additives, the following comparisons of three types were carried out; (a), (b) and (c).

(a) Without additives

(b) a general dispersing agent (zinc stearate)

(c) a compatibilizer (a graft modified polymer)

The results will be explained with reference to Figure 17 which shows the measurement results. In addition, in Figure 17, the circles refer to resin materials using Sample 1 of the comparative example, and the squares refer to resin materials using Sample 5 of Example 1.

In case (a) where no additive was added, the difference between tensile strengths was small.

In case (b) where dispersing agent was added, it was found that in the graphene precursor of Sample 5 the formation of graphene was stimulated to some extent.

In case (c) where the compatibilizer was added, it was found that graphene formation was significantly promoted in the graphene precursor of Sample 5. This is because it is considered that, in addition to the dispersion effects of graphene, the compatibilizer It binds the bodies attached to the graphene layer and the resin, and acts on them so that the bodies attached to the graphene layer are torn from it, when shearing is applied in that state.

Zinc stearate has been explained above as an example of dispersing agent. However, those that are appropriate for the compounds can be selected. As examples of dispersing agent there may be mentioned anionic surfactants (anion), cationic surfactants (cation), zwitterionic surfactants and non-ionic surfactants. In particular, anionic surfactants and nonionic surfactants are preferable for graphene. Most preferable are nonionic surfactants. Since non-ionic surfactants are surfactants that do not dissociate into ions and show hydrophilic properties due to hydrogen bonds with water, as observed in oxyethylene groups, hydroxyl groups, carbohydrate chains such as glucoside, and the like, they have the advantage that they can be used in solvents not

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polar although they do not possess the strong hydrophilic character of ionic surfactants. Furthermore, this is because, by varying the chain lengths of their hydrophilic groups, their properties can be freely changed from lipophilic properties to hydrophilic properties. As anionic surfactants, salts of acid X (examples of acid X colic acid and deoxycholic acid) are preferred, for example, SDC: sodium deoxycholate, and phosphate esters. Also, as non-ionic surfactants, glycerol fatty acid esters, sorbitan fatty acid esters, fatty alcohol ethoxylates, polyoxyethylene alkyl phenyl ether, alkyl glycosides and the like are preferable.

Example 5

To further verify that the products obtained when the proportion (3R) is 31% or greater are beneficial as graphene precursors, as described above in Example 1, an example in which Knead a graphene precursor with a resin. The following explains the elastic modules of the resin molded articles in which the graphite-based carbon materials containing Samples 1 to 7 of Example 1, which had the Proportions (3R) represented in Figure, were used as precursors 14.

(1) Using the graphite-based carbon material described above as a precursor, 5% by weight of LLDPE (polyethylene: 20201J produced by Prime Polymer Co., Ltd.) and 1% by weight of a dispersant (surfactant not ionic) in ionic exchange water, and the device described above illustrated in Figure 8 was operated under the same conditions, whereby graphene dispersions containing 5% by weight of graphene and graphite-based carbon materials were obtained .

(2) 0.6 kg of the graphene dispersion that was obtained in (1) within a 5.4 kg resin was immediately kneaded using a kneader (pressure type WDS7-30 produced by Moriyama Co., Ltd.), whereby granules were produced. Kneading conditions will be described below. Note that the mixing ratio between the resin and the dispersion was selected such that the amount of graphene and the graphite-based carbon materials that were mixed was finally 0.5% by weight.

(3) The granules produced in (2) formed a test piece in accordance with JIS K7161 1A (length: 165 mm, width: 20 mm, thickness: 4 mm) by means of an injection molding machine.

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(4) The elastic modulus (MPa) of the test piece that was produced in (3) was measured under conditions of a test speed of 500 mm / min according to JIS K7161 using a universal precision type testing machine Bank produced by Shimadzu Corporation (AUTOGRAPH AGS-J).

Kneading conditions were as follows.

Kneading temperature: 135 ° C

Rotation speed of the rotor: 30 rpm

Kneading time: 15 minutes

Oven pressurization: applying 0.3 MPa for 10 minutes after the start, and depressurizing at atmospheric pressure after 10 minutes.

At this point, the dispersion of the graphene dispersion described above within a resin is considered as follows. Since the melting point of the resin is generally 100 ° C or higher, the water evaporates in the atmosphere, but in a pressure-type mixer the interior of the oven can be pressurized. Inside the furnace, the boiling point of the water rises such that the dispersion is maintained in liquid form, whereby an emulsion of the dispersion and the resin can be obtained. After applying pressure for a predetermined time, the interior gradually depressurizes, which causes the boiling point of the water to decrease, thereby allowing the water to evaporate. At this point, graphene confined in water is left in the resin. This causes graphene and graphite-based carbon materials to disperse in the resin with a high concentration.

Furthermore, since graphene and graphite-based carbon materials tend to precipitate in the graphene dispersion as time goes by, preferably the graphene dispersion is kneaded into the resin immediately after obtaining the graphene dispersion.

Note that the following can be used as a means to obtain the emulsion of the dispersion and the resin, different from the pressure kneader: a chemical propellant; a vortex mixer; a homomixer; a high pressure homogenizer; a hydro-shearing machine; a flow jet mixer; a hydraulic jet mill; and an ultrasonic generator.

In addition, the following may be used as a solvent for dispersion, other than water: 2-propanol (IPA); acetone; Toluene; N-methylpyrrolidone (NMP); and N, N-dimethyl formamide (DMF).

Table 4 illustrates the relationship between Proportions (3R) of approximately 30% and the elastic moduli of resin molded articles. Note that the Sample

00 of Table 4 is a blank sample in which no precursor was kneaded, Samples 11 and 12 have Proportions (3R) between that of Sample 1 and that of Sample 2, and Sample 21 has a Proportion ( 3R) between that of Sample 2 and that of Sample 3.

{Table 4}

 Sample No.

 00 1 11 12 2 21 3 4

 P3 / (P3 + P4)

 _ 23% 25% 28% 31% 35% 38% 42%

 Elastic module (MPa) (5 times average)

 175 197 196 199 231 249 263 272

 White difference

 - 12.4% 12.0% 13.9% 31.7% 42.1% 50.0% 55.6%

 Less than 10 layers when dispersed in NMP (Reference)

 - 10% 12% 25% 25% 30% 38% 62%

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Figure 18 and Table 4 prove that the difference of the elastic module with respect to that of Sample 00 (white) (ratio of increase of the elastic module) is approximately uniform and around 10% until the Proportion (3R) reaches 31 %; after the Proportion (3R) reaches 31%, the difference increases sharply to 32%; while the Proportion (3R) increases from 31% to 42%, the difference increases monotonously to 50%; and after the Proportion (3R) reaches 42%, the difference increases slightly and converges to approximately 60%. In this way, when the Proportion (3R) is 31% or greater, a resin molded article having an excellent elastic modulus can be obtained. In addition, since the amount of graphene and graphite-based carbon materials contained in a resin molded article is 0.5% by weight, which is little, the influence on the properties that the resin originally possesses is small.

This trend is considered to be attributed to a sharp increase in a thin graphite-based carbon material containing graphene that has 10 or less layers in contact with the resin after the Proportion (3R) reaches 31%. At this point, in Example 5, it is impossible to determine the number of graphene layers by an observation with MET due to the influences of the dispersant that is used to obtain the dispersion in water. Therefore, only as a reference, the reason for the

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The sharp increase described above is based on the distribution of the numbers of layers of the graphite-based carbon material illustrated in Table 4 when dispersed in NMP. Sample 12 and Sample 2 were compared to each other, and it was found that both graphene ratios (the number of layers is 10 or less) were 25%. On the other hand, as illustrated in Figure 19, with respect to Sample 2, the proportion among thin materials with less than 15 layers was higher compared to Sample 12; in other words, the dispersed graphite-based carbon material as a precursor had a greater surface area, which means that the area of the same in contact with the resin increased sharply.

Thus, Example 5 clearly indicates that when Proportion (3R) is 31% or greater, a graphite-based carbon material used as a graphene precursor tends to separate into graphene that has 10 or less layers and a material. thin carbon based graphite.

Example 6

In Example 5 where only graphene-type graphite was dispersed, an elastic modulus was increased, however, a significant increase in tensile strength was not observed.

Therefore experiments were carried out by adding the graphene precursor produced by the above methods and a glass fiber to a resin.

<Various conditions>

Resin: PP (polypropylene) J707G manufactured by Prime Polymer Co., Ltd.,

Compatibilizer: KAYABRID (006PP manufactured by Kayaku Akzo Corp. PP modified with maleic anhydride)

Fiberglass (GF): ECS03-631K manufactured by Central Glass Fiber Co., Ltd. (13 pm diameter, 3 mm length),

Graphite-based carbon material: graphene precursor (obtained by the previous method),

Mixer: Drum mixer (manufactured by SEIWA GIKEN Co., Ltd.), <Mixing condition 1: rotation speed 25 rpm x 1 min>,

Kneader: two-axis extruder (HYPERKTX 30 manufactured by Kobe Steel, Ltd.), <Kneading condition 1: 180 ° C cylinder temperature, 100 rpm rotor rotation speed, 8 kg / h discharge speed>

Test piece: JIS K7139 (170 mm x 20 mm x t4 mm),

Measuring device: AUTOGRAPH AGS-J exact bank general purpose test machine manufactured by Shimadzu Corp.

<Experimental procedures>

Stage 1. 40% by weight of a fiberglass (GF), 4% by weight of a compatibilizer and 56% by weight of a resin are pre-mixed in a drum mixer in the mixing condition 1 , and then kneaded with a two-axis extruder in kneading condition 1 to obtain a master batch 1.

Step 2. 12% by weight of a graphene precursor having a different proportion (3R) as shown in Table 5 and 88% by weight of a resin are pre-mixed with a drum mixer under the condition mixing 1, and then knead with a two-axis extruder in kneading condition 1 to obtain a master batch 2.

Step 3. 25% by weight of master batch 1, 25% by weight of master batch 2 and 50% by weight of a resin are pre-mixed with a drum mixer under mixing condition 1, and then Knead with a two-axis extruder in kneading condition 15.

Stage 4. A kneaded mixture obtained in Stage 3 was formed to give a test piece with an injection molding machine and the changes in its mechanical strength were observed at a test speed of 500 mm / min according with JIS K7139.

20 To confirm an effect of graphene-type graphite experiments were performed

with a ratio (3R) of 23% (Sample 1), 31% (Sample 2), 35% (Sample 21) and 42% (Sample 4) with a mixing ratio shown in Table 5.

Table 5

to

VO

 Mixing ratio (% by weight) Tensile strength (MPa) Flexural modulus (GPa)

 PP

 GF Graphene Precursor Compatibilizer

 proportion (3R) = 23% (Sample 1)

 Proportion (3R) = 31% (Sample 2) Proportion (3R) = 35% (Sample 21) Proportion (3R) = 42% (Sample 4)

 Example 6-1

 86 1 10 3 _ _ 73 3.9

 Example 6-2

 86 1 10 _ 3 _ _ 99 5.6

 Example 6-3

 86 1 10 _ _ 3 _ 108 6.2

 Example 6-4

 86 1 10 _ _ _ 3 116 6.5

 Comparative Example 6-1

 100 - - - - - - 25 1.2

 Comparative Example 6-2

 89 1 10 - - - - 70 3.8

 Comparative Example 6-3

 96 1 - - 3 - - 27 2.5

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According to Table 5 and Figure 20, it was observed that the tensile strength in Examples 6-2, 6-3 and 6-4 was greater than in Example 6-1 and Comparative Examples 6-1, 6- 2 and 6-3. In particular, when the proportion (3R) of the graphene precursor reached 31% or more, a notable trend in tensile strength was observed, which increased by 30% or more compared to the cases in which the proportion (3R ) was 0% (Comparative Example 6-2) and the proportion (3R) was 23% (Example 6-1).

Actually, the cases in Example 6-2 do not denote a Proportion (3R) = 0%. As the graphene precursor was not added, the 0% data should not be shown in the same graph; However, they are shown for convenience. From here on, 0% has the same meaning.

Note that the data in Comparative Examples 6-1 and 6-3, in which GF is not included, is not shown in Figure 20.

Furthermore, similarly in the case of tensile strength, it was observed that the flexural modulus in Examples 6-2, 6-3 and 6-4 was greater than in Example 6-1 and Comparative Examples 6 -1, 6-2 and 6-3. In particular, when the proportion (3R) of the graphene precursor reached 31% or more, a notable trend in the flexural modulus was observed, which increased by 40% or more compared to the cases in which the proportion (3R) it was 0% (Comparative Example 6-2) and the proportion (3R) was 23% (Example 6-1).

When graphene precursors having a ratio (3R) of 31% or more (Examples 6-2, 6-3 and 6-4) are used together with GF, tensile strength and flexural modulus increase. This is because it is speculated that graphene-type graphite having a thickness of 0.3 to several tens of nm and a size of several nm to 1 pm is dispersed in PP, thereby increasing an elastic modulus of the PP itself , and at the same time, graphite of graphene type was contacted with GF, which was closely linked to the PP by virtue of a compatibilizer leaving this way hardly from the PP, a so-called cradle action is carried out in the GF. As a result, both tensile strength and flexural modulus were increased by a synergistic effect of increasing an elastic modulus of the PP itself and performing a cradle action. This situation can be expressed by the following parable: after driving a stake with spikes on the ground, it can easily leave a muddy ground, but it can hardly leave a well trodden earth. As another factor that causes this, it is speculated that the addition of the compatibilizer promotes the exfoliation of graphene-type graphite, etc. of the graphite-based carbon material, thereby causing graphene-like graphite in flakes to be present in a larger amount.

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When the proportion (3R) is less than 31%, (Example 6-1), the amount of graphene-type graphite that is dispersed is considered to be too small, so that an effect of adding a precursor is not sufficiently exerted of graphene

When the proportion (3R) is 35% or more (Examples 6-3 and 6-4), the flexural modulus and tensile strength are excellent compared to cases where the proportion (3R) is equal or less than that. The reason is considered to be that the amount of graphene-type graphite that causes an increase in an elastic modulus of the PP increases compared to the case in which the proportion (3R) is 31% (Example 6-2).

For reference, an explanation is given in the photographed images of graphene precursors taken by means of a scanning electron microscope (SEM). The graphene precursors obtained in example 1 are a flake graphite laminate having a length of 7 pm and a thickness of 0.1 pm, as shown for example in Figures 21 and 22.

In addition, graphene-type graphite dispersed in a resin can be observed by a scanning electron microscope (MEB) and the like after being formed in a test piece and cut by a high-speed precision saw (TechCut5 manufactured by Allied High Tech Products , Inc.) and the like. For example, Figure 23 shows a cross section of a resin in which a carbon nanotube and a graphite of graphene type are dispersed, where the carbon nanotube is represented by a linear part and graphite of graphene type is represented by a blank dotted part Graphene type graphite is a flake graphite laminate that is 3.97 nm thick, as shown for example in Figure 24.

Example 7

Experiments were performed to obtain a resin molded article using the graphene precursor produced in the above methods.

<Various conditions>

Resin: PA66 (nylon 66) 1300S manufactured by Asahi Kasei Corp.,

Compatibilizer: KAYABRID (006PP manufactured by Kayaku Akzo Corp. PP modified with maleic anhydride)

Fiberglass (GF): ECS03-631K (13 pm diameter, 3 mm length) manufactured by Central Glass Fiber Co., Ltd.,

Graphite-based carbon material: graphene precursor (obtained by the above methods),

Mixer: Drum mixer (manufactured by SEIWA GIKEN Co., Ltd.),

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<Mixing condition 1: rotation speed 25 rpm x 1 min>,

Kneader: two-axis extruder (HYPERKTX 30 manufactured by Kobe Steel, Ltd.), <Kneading condition 2: 280 ° C cylinder temperature, 200 rpm rotor rotation speed, 12 kg / h discharge speed> ,

Test piece: JIS K7139 (170 mm x 20 mm x t4 mm),

Measuring device: AUTOGRAPH AGS-J exact bank general purpose test machine manufactured by Shimadzu Corp.

<Experimental procedures>

Stage 1. 40% by weight of a fiberglass (GF), 4% by weight of a compatibilizer and 56% by weight of a resin are pre-mixed in a drum mixer in mixing condition 1, and then they are kneaded with a two-axis extruder in kneading condition 2 to obtain a master batch 1.

Step 2. 12% by weight of a graphene precursor having a different proportion (3R) as shown in Table 6 and 88% by weight of a resin are pre-mixed with a drum mixer in the condition of mixed 1, and then kneaded with a two-axis extruder in kneading condition 2 to obtain a master batch 2.

Step 3. 37.5% by weight of master batch 1, 25% by weight of master batch 2 and 37.5% by weight of a resin are pre-mixed with a drum mixer in mixing condition 1 , and then kneaded with a two-axis extruder in kneading condition 2.

Stage 4. The kneaded mixture obtained in Stage 3 was formed to give a test piece with an injection molding machine and the changes in the mechanical resistance thereof were observed at a test speed of 500 mm / min according to with JIS K7139.

To confirm an effect of graphene-type graphite, experiments were performed with a proportion (3R) of 23% (Sample 1), 31% (Sample 2), 35% (Sample 21) and 42% (Sample 4) with a ratio of mixture shown in Table 6.

{Table 6}

U>

U>

 Mixing ratio (% by weight) Tensile strength (MPa) Flexural modulus (GPa)

 PA66

 GF Graphene Precursor Compatizer

 proportion (3R) = 23% (Sample 1)

 Proportion (3R) = 31% (Sample 2) Proportion (3R) = 35% (Sample 21) Proportion (3R) = 42% (Sample 4)

 Example 7-1

 80.5 1.5 15 3 _ _ 111 4.9

 Example 7-2

 80.5 1.5 15 _ 3 _ _ 138 6.2

 Example 7-3

 80.5 1.5 15 _ _ 3 _ 143 6.6

 Example 7-4

 80.5 1.5 15 ___ 3 146 6.8

 Comparative Example 7-1

 100 - - - - - - 57 2.7

 Comparative Example 7-2

 83.5 1.5 15 - - - - 107 4.8

 Comparative Example 7-3

 95.5 1.5 - - 3 - - 90 3.3

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According to Table 6 and Figure 25, it was observed that the tensile strength in Examples 7-2, 7-3 and 7-4 was greater than in Example 7-1 and Comparative Examples 7-1, 7- 2 and 7-3. In particular, when the proportion (3R) of the graphene precursor reached 31% or more, a notable trend in tensile strength was observed, which increased by 20% or more compared to the cases in which the proportion (3R ) was 0% (Comparative Example 7-2) and the proportion (3R) was 23% (Example 7-1). Note that the data in Comparative examples 7-1 and 7-3, in which GF is not included, is not shown in Figure 25.

Also, similarly in the case of tensile strength, it was observed that the flexural modulus in Examples 7-2, 7-3 and 7-4 was greater than in Example 7-1 and Comparative Examples 7 -1, 7-2 and 7-3. In particular, when the proportion (3R) of the graphene precursor reached 31% or more, a notable trend in a flexural modulus was observed, which increased by 20% or more compared to the cases in which the proportion (3R) it was 0% (Comparative Example 7-2) and the proportion (3R) was 23% (Example 7-1).

The tensile strength and flexural modulus are considered to be improved for the same reason as explained in Example 6.

According to Examples 6 and 7, it was observed that tensile strength and flexural modulus improved regardless of whether a resin served as the base material. An explanation is given in a case where a graphene precursor is added together with GF. When graphene precursors had the Proportion (3R) of 23% (Examples 61 and 7-1), it was observed that a tensile strength and a flexural modulus improved slightly regardless of whether a resin served as a base material in comparison with cases where a graphene precursor was not added (Comparative Examples 6-2 and 7-2), while when the graphene precursors used had the Proportion (3R) of 31% or more, it was observed that resistance to traction and flexural modulus were greatly enhanced (10% or more).

Example 8

The experiments were performed by adding the graphene precursor produced in the above methods and a resin reinforcing material.

In Example 8, a glass fiber (GF), a carbon fiber (CF), talc and silica were used as a reinforcing material to confirm an effect caused by a form of a reinforcing material. Except for the reinforcement material, the experimental and similar conditions are the same as in Example 6.

As shown in Figure 27, GF and CF, which function as a reinforcing material, have a diameter of several tens of qm and a length of several hundreds of qm in a wire or linear type. The talc has a representative length of several qm to several tens and a thickness of several hundred nm in a flake-like form, 5 while the silica has a diameter of several nm to several tens in a form

particulate

{Table 7}

 Mixing ratio (% by weight) Tensile strength (MPa) Flexural modulus (GPa)

 PP

 Compatibilizer GF CF Talco Silice Graphene precursor proportion (3R) = 31% (Sample 2)

 Example 6-2

 86 1 10 3 99 5.6

 Example 8-1

 86 1 10 3 168 6.7

 Example 8-2

 86 1 10 3 45 4.0

 Example 8-3

 86 1 10 3 33 3.8

 Comparative Example 6-2

 89 1 10 - - - - 70 3.8

 Comparative Example 8-1

 89 1 - 10 - - - 130 5.2

 Comparative Example 8-2

 89 1 - - 10 - - 35 3.5

 Comparative Example 8-3

 89 1 - - - 10 - 32 1.9

 Comparative Example 6-1

 100 - - - - - 25 1.2

As shown in Table 7 and Figure 26, the tensile strength and flexural modulus are improved in all cases where a reinforcing material is added compared to Comparative Example 6-1 where no one is added. reinforcement material. A comparison was made between cases where a reinforcement material and a graphene precursor were added (Examples 6-2, 8-1, 8-2 and 8-3) and cases where only a reinforcement material was added (Comparative Examples 6-2, 8-

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1, 8-2 and 8-3). When GF was added as a reinforcing material together with a graphene precursor, both tensile strength and flexural modulus improved 1.4 times and 1.4 times, respectively (a rate of change observed in Example 6- 2 with respect to comparative example 6-2). Similarly, tensile strength and flexural modulus improved 1.3 times and 1.3 times respectively in the case of CF, 1.3 times and 1.1 times respectively in the case of talc, and 1, 0 and 2.0 times respectively in the case of silica. From this it was discovered that the use of a reinforcement material in a wire, linear or flake type form together with a graphene precursor improved tensile strength and flexural modulus by 10% or more, thereby being preferable. It is speculated that a nano-reinforcing material in a wire, linear or flake type form, having a large surface area per unit mass due to its shape, is highly effective in improving tensile strength, as well as being able to increase a flexion module, therefore it has high compatibility with graphene type material. It was also revealed that, as a reinforcing material in a wire, linear or flake type form, the one having an aspect ratio of 5: 1 or more is particularly preferable. In contrast, a reinforcing material that has an aspect ratio of 5: 1 or less, such as silica, resulted in an increase in the flexural modulus only. Note that the aspect ratio of a material having a flake-like shape can be obtained by calculating the ratio of an average thickness to a length of the longest part. The aspect ratio mentioned herein can be calculated using the average value of a diameter or a thickness and the average value of a length, described in a catalog and the like of a reinforcing material. Especially, when a catalog and the like are not available, a material is observed by an electron microscope such as SEM in an arbitrary number to obtain average values of length and thickness thereof, from which an aspect ratio is calculated.

Example 9

Next, experiments were performed to obtain a resin molded article using the graphene precursor produced in the above methods.

The experiments were performed with a mixture ratio of the graphene precursor having the proportion (3R) of 31% to a reinforcing material under the conditions shown in Table 8. The experimental conditions and the like are the same as in Example 6 .

{Table 8}

 Mixing ratio (% by weight) Tensile strength (MPa) Flexural modulus (GPa)

 PP

 GF Graphene Precursor Compatizer

 Proportion (3R) = 31% (Sample 2)

 Example 9-1

 88 1 10 1 87 4.7

 Example 6-2

 86 1 10 3 99 5.6

 Example 9-2

 84 1 10 5 107 6.3

 Example 9-3

 81 1 10 8 116 6.9

 Example 9-4

 79 1 10 10 120 7.1

 Example 9-5

 74 1 10 15 121 7.2

 Example 9-6

 88.5 1 10 0.5 80 4.5

 Example 9-7

 88.7 1 10 0.3 79 4.2

 Example 9-8

 88.9 1 10 0.1 73 4.0

 Comparative Example 6-1

 100 - - - 25 1.2

 Comparative Example 6-2

 89 1 10 - 70 3.8

As shown in Table 8 and Figure 28, when the mixing ratio of the graphene precursor to the reinforcing material became greater than 1 (Example 9-4), it was observed that the tensile strength and modulus of Flexion remained almost at the same values and its characteristics became saturated. Furthermore, when the mixing ratio of the graphene precursor is 10 or more, an impact on the properties of a base material becomes significant. On the other hand, when the mixing ratio was 1/100 (Example 9-8), it was observed that tensile strength and flexural modulus increased 4% 10 or more and 10% or more, respectively, in comparison with Comparative Example 62 where a graphene precursor was not added. In addition, it was observed that tensile strength increased sharply when the mixing ratio was 1/10 (Example 6-2) or

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more, while the flexion module increased sharply when the mixing ratio was 1/3 (Example 9-1) or more.

Based on this, the lower limit of the mixing ratio is 1/100 or more, preferably 1/10 or more, and the upper limit thereof is 10 or less, preferably 1 or less.

Note that the data in Comparative Example 6-1 where GF is not included is not represented in Figure 28.

In Example 6-9, the graphene precursor is produced by a first treatment based on radio wave forces and / or a second treatment based on physical force as described above, so it is not necessary to perform a treatment of oxidation / reduction. In addition, since a reduction treatment is not necessary to produce a test piece, high temperature is not required, as a result the production of a test piece is easily performed.

The foregoing explained the embodiments of the present invention using figures, however, it should be understood that the specific constitutions are not entirely restricted to these embodiments, and changes and additions are also included in the present invention without departing from the essence of the present invention.

Examples of a base material for dispersing a reinforcing material and a graphite-based carbon material include the following. Note that a mixing ratio of a base material may be less than that of a reinforcing material or a graphite-based carbon material. In addition, a base material can be annihilated by combustion, oxidation, vaporization, evaporation and the like when in use. For example, when a base material such as a coating agent and the like is a volatile solvent, the base material is charred by combustion, as in the case of a C / C compound.

Examples of a resin include thermoplastic resins such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), ABS resins (ABS), polylactic acid (PLA), acrylic resins (PMMA), polyamide / nylon (PA), polyacetal (POM), polycarbonate (PC), polyethylene terephthalate (PET), cyclic polyolefin (COP), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyamide-imide ( PAI), thermoplastic polyimide (PI), polyether ether ketone (PEEK), crystalline polymers (LCP) and the like. In addition, synthetic resins such as thermosetting resins or UV curing resins include epoxy resins (EP), phenolic resins (PF), melamine resins (MF), polyurethanes (PUR) and unsaturated polyester resins (UP) and Similar; as conductive polymers include PEDOT,

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polythiophene, polyacetylene, polyaniline, polypyrrole and the like; Fibers include fibrous nylon, polyester, acrylic, vinalon, polyolefin, polyurethane, rayon and the like; Elastomers include isoprene rubbers (IR), butadiene rubbers (BR), styrene / butadiene rubbers (SBR), chloroprene rubbers (CR), nitrile rubbers (NBR), polyisobutylene rubbers / butyl rubbers (IIR ), ethylene propylene rubbers (EPM / EPDM), chlorosulfonated polyethylene (CSM), acrylic rubbers (ACM), epichlorohydrin rubbers (CO / ECO), and the like; as elastomers based on thermosetting resins, some urethane rubbers (U), silicone rubbers (Q), fluorine containing rubbers (FKM) and the like are included; and, as thermoplastic elastomers, elastomers based on styrene, olefin, polyvinyl chloride, urethane and amide are included.

Examples of an inorganic material include concrete, ceramics, plaster, metal powders and the like.

Examples of a reinforcing material include the following.

As a metallic material are included silver nanoparticles, copper nanoparticles, silver nanowires, copper nanowires, flaked silver, flaked copper, iron powders, zinc oxide, fibrous metal (boron, tungsten, alumina and silicon carbide ) and the like.

Carbon materials include carbon black, carbon fibers, CNT, graphite, activated carbon and the like.

As a non-metallic material except for carbon, glass fibers, nanocelluloses, nano-clay (clay ore such as montmorillonite), aramid fibers, polyethylene fibers and the like are included.

In addition, as an example of natural graphite to produce a graphite-based carbon material useful as a precursor to graphene, particles of 5 mm or less of a natural graphite material have been described above (graphite in ACB-50 flakes manufactured by Nippon Graphite Industries, Ltd.). However, in terms of natural graphite, the preferable products are graphite in flakes that are sprayed up to 5 mm or less, and that have a Proportion (3R) of less than 25% and a lower P1 / P2 intensity ratio 0.01, from the perspective that they are easily obtainable. Corresponding to the recent development of the technology, natural graphite type graphite (in which the crystals are stacked in layers) can be synthesized artificially, in this way the raw materials for graphene and graphene type graphite are not limited to natural graphite (mineral) . Artificial graphite having a high degree of purity is preferably used in order to control a metal content. In addition, provided that the Proportion (3R) is 31% or

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In addition, artificial graphite can be used, which is not produced by the physical force based treatment or the radio wave force based treatment described above.

Note that a graphite-based carbon material useful as a graphene precursor is generally called graphene, a graphene precursor, a graphene nanoplate (GNP), low-layer graphene (FLG), nanograph and the like, however, no It is particularly limited to them.

Industrial applicability

The present invention encompasses a composite reinforcement material that has strength, and a field of application thereof is not limited. For example, the following fields are included in the present invention.

(1) Examples in which a base material is an organic material (resins and plastics)

(1-1) Means of transport for transport

Airplanes, cars (passenger cars, trucks, buses, etc.), boats, toy housings, etc., members of structures such as parts (for members of structures, composite resins, modified resins, fiber reinforced resins and the like)

(1-2) General Purpose Items

Furniture, appliances, household items, toy housings, etc., members of structures such as parts.

(1-3) 3D printers

Various kinds of molding materials, such as resin filaments and UV curing resins, used in molten deposition modeling (FDM), stereolithography (SLA), powder fixing lamination, selective laser sintering (SLS) and modeling multi injection (MJM, inkjet modeling).

(1-4) Coating Agents

A composite reinforcing material, together with a resin, is dispersed in an organic solvent and used to coat a surface of objects by spraying or painting, etc. Such a coating agent improves the strength of the objects and also has effects of water repellency, corrosion resistance, resistance to ultraviolet rays, etc. Examples of application include use for external and internal coating of constructions (bridge pillars, buildings, walls, roads, etc.), automobiles, airplanes, etc., and for resin molded articles, such as helmets and protectors.

(2) Examples in which a base material is an inorganic material Members of fiber reinforced structures, such as cement (concrete,

mortar), fibroyeso panels, ceramics and C / C compounds (carbon composite materials reinforced with carbon fiber). Products manufactured by dispersing graphite of 5 graphene type and a reinforcing material in these inorganic materials as a base material.

(3) Metal materials as a base material

Members of structures, such as aluminum, stainless steel, titanium, brass, bronze, soft steel, nickel alloy and tungsten carbide (for members of 10 structures, fiber reinforced metal and the like). Products that are manufactured by dispersing graphene-type graphite and a reinforcing material in these metallic materials as a base material.

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1. - A composite reinforcement material, characterized in that it comprises at least one graphite-based carbon material and a reinforcing material dispersed in a base material,

the graphite-based carbon material having a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), where the Proportion (3R) of the rhombohedral graphite layer (3R) and the hexagonal graphite layer ( 2H), based on an X-ray diffraction method that is defined by the following Equation 1, is 31% or more:

Proportion (3R) = P3 / (P3 + P4) * 100 •••• (Equation 1)

in which

P3 is the peak intensity of a plane (101) of the rhombohedral graphite layer (3R) based on the X-ray diffraction method, and

P4 is the peak intensity of a plane (101) of the hexagonal graphite layer (2H) based on the X-ray diffraction method.

2. - The composite reinforcement material according to claim 1, characterized in that the reinforcement material is a microparticle having a wire, linear or flake-like shape.

3. - The composite reinforcement material according to claim 2, characterized in that the microparticle has an aspect ratio of 5: 1 or more.

4. - The composite reinforcement material according to claim 1 or 2, characterized in that the weight ratio of the graphite-based carbon material to the reinforcement material is 1/100 or more, and less than 10.

5. - The composite reinforcement material according to claim 1, characterized in that the base material is a polymer.

6. - The composite reinforcement material according to claim 1, characterized in that the base material is an inorganic material.

Claims (2)

10 fifteen 7. A method of obtaining a composite reinforcing material, characterized in that it comprises dispersing at least one carbon material based on graphite and a reinforcing material in a base material, thus exfoliating a part or all of said carbon material based on graphite, the graphite-based carbon material having a rhombohedral graphite layer (3R) and a hexagonal graphite layer (2H), where the Proportion (3R) of the rhombohedral graphite layer (3R) and the hexagonal graphite layer ( 2H), based on an X-ray diffraction method that is defined by the following Equation 1, is 31% or more: Proportion (3R) = P3 / (P3 + P4) * 100 •••• (Equation 1) in which P3 is the peak intensity of a plane (101) of the rhombohedral graphite layer (3R) based on the X-ray diffraction method, and P4 is the peak intensity of a plane (101) of the hexagonal graphite layer (2H) based on the X-ray diffraction method. image 1